For others who were curious about what time difference this makes: looks like sex identification is possible at 9 days after the egg is laid, vs 21 days for the egg to hatch (plus an additional ~2 days between fertilization and the laying of the egg.) Chicken embryonic development is really fast, with some stages measured in hours rather than days.
I asked Google when chicken embryos start to feel pain and this was the first result (i.e. I didn’t look hard and I didn’t anchor on a figure):
A recent study by the Technical University of Munich in Germany measured chicken embryos’ heart rate, brain activity, blood pressure and movements in response to potentially painful stimuli like heat and electricity and concluded that they didn’t seem to feel them until at least day 13. (14 Oct 2023)
For others who were curious about what time difference this makes: looks like sex identification is possible at 9 days after the egg is laid, vs 21 days for the egg to hatch (plus an additional ~2 days between fertilization and the laying of the egg.) Chicken embryonic development is really fast, with some stages measured in hours rather than days.
I asked Google when chicken embryos start to feel pain and this was the first result (i.e. I didn’t look hard and I didn’t anchor on a figure):